The function and the synthesis of the polypeptide product of the src gene of Rous sarcoma virus in transformed chick cells will be studied. The intracellular location of this polypeptide will be determined by cell fractionation and immunoprecipitation, and by immunofluorescence, in Schmidt-Ruppin RSV-D transformed chick cells. New anti-sera which recognize the products of the src genes of strains of RSV other than the Schmidt-Ruppin strain will be produced. The src gene products of the various strains of RSV will be compared in cultured cells. The interaction of the src gene product with mammalian and avian cells will be compared. The interaction of viral glycoproteins with cellular and viral membranes will be examined. The amino termini of the glycoproteins of Sindbis virus will be characterized in order to see whether they resemble in structure and function the signal peptides of presecretory proteins. The conformation of viral glycoproteins in membranes will be characterized by the use of inside-out membrane vesicles, selectively permeable labeling agents and proteolysis. The generality of the asymmetric distribution of phospholipids within lipid bilayers will be examined by comparing the accessibility of the phospholipids in virions of Sindbis virus and VSV, grown in a variety of host cells, to phospholipases and to phospholipid exchange proteins.